Influence of incubation time and action of fluid flow on SPEV cell adhesion strength to a glass substrate

The results of study of SPEV cell adhesion to the glass substrate that were obtained with a radial-flow chamber shown that in some cases the cells which were incubated on the substrate for a longer time were more strongly attached to it, and under certain conditions such cells detached easier than cells with a shorter incubation time. For example, when the channel height was decreased more of cells were detached from substrate with increasing incubation time. Besides an increase of flow action time on the cells increased an amount of detached cells, and an increase of initial shear stress resulted in decrease an amount of cells which detached from the surface regardless of incubation time. During each experiment more spread cells detached from the substrate earlier than the more spherical one. When both the flow rate and channel height were reduced in the radial-flow chamber, but the initial shear stress was the same as before the changes of these parameters, then the critical radius, the critical shear stress and the time of reach these critical values sharply decreased. In addition, in this case, the area of the projection of cells remaining on the substrate also decreased.     

Effectiveness of different surface cleaning methods on the shear bond strength of resin cement to contaminated zirconia: an in vitro study

The purpose of this in vitro study was to evaluate and compare the effectiveness of different surface cleaning methods on the shear bond strength (SBS) of zirconia ceramic surfaces. Seventy polished and cleaned zirconia disk specimens of 8 mm in diameter and 3.4 mm in thickness were immersed in fresh saliva. They were then pressed into a freshly mixed silicone disclosing medium. Six different cleaning methods were applied to the tested groups; they were airborne-particle abraded (AA), covered with a cleaning paste (Ivoclean®) (IV), etched with orthophosphoric acid (PA), immersed in alcohol (AL), rinsed with tap water only (WA), or cleaned with steam (SC). No surface cleaning was done after saliva immersion and silicone disclosing medium contamination to the control group (CC). The specimens were then bonded to an adhesive resin cement using polyethylene tubes. SBS was determined using a universal testing machine at a crosshead speed of 1 mm/min. The specimens were also examined with a scanning electron microscope and a stereomicroscope. Group AA yielded the highest SBS value (7.01 ± 1.4 MPa) among the groups, while Group WA had the lowest SBS value (3.03 ± 0.8 MPa). The SBS values of Group AA (7.01 ± 1.4 MPa) and IV (6.2 ± 1.7 MPa) were also significantly higher than those of the remaining four groups (p < 0.05). Within the limitations of this in vitro study, it was concluded that among the various cleaning methods tested, airborne-particle abrasion and Ivoclean® paste were effective in cleaning the zirconia surface.